Precipitation of polyether block amide and thermoplastic polyethylene to enhance operational window for three dimensional printing

ABSTRACT

A polymer material suitable for three-dimensional printing that may include at least one of polyether block amide, thermoplastic polyeurothane, and thermoplastic olefin. The polymer is formed through chemical precipitation forming a precipitated pulverulent polymer which possesses increased operating window characteristics selected from the group consisting at least one of a wider than typical range between and among the melting and recrystallization temperatures, a larger enthalpy upon melting, and a low volumetric change during recrystallization.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority to PCTApplication No. PCT/US2017/056996, filed Oct. 17, 2017, entitled“PRECIPITATION OF POLYETHER BLOCK AMIDE AND THERMOPLASTIC POLYETHYLENETO ENHANCE OPERATIONAL WINDOW FOR THREE DIMENSIONAL PRINTING,” whichclaims priority to Provisional Application No. 62/409,036, filed Oct.17, 2016, entitled “PRECIPITATION OF POLYETHER BLOCK AMIDE ANDTHERMOPLASTIC POLYETHYLENE TO ENHANCE OPERATIONAL WINDOW FOR THREEDIMENSIONAL PRINTING,” which are herein incorporated by reference intheir entirety.

BACKGROUND Field of the Disclosure

The present disclosure relates to materials and methods of making samefor additive manufacturing, and, more particularly, to precipitatedpulverulent Polyether block amide (PEBA), thermoplastic olefin (TPO),and thermoplastic polyurethane (TPU) having increased operating windowsfor additive manufacturing applications.

Description of the Background

Additive manufacturing, commonly known as three-dimensional printing(3D-printing), constitutes a significant advance in the development ofnot only printing technologies, but also of product development,prototyping, and experimental capabilities. Capabilities of 3D-printinginclude forming physical objects of virtually any geometry. By way ofnon-limiting example, gears, sprockets, toys, models, prototypes, andcountless other physical objects can now be built using a 3D printer.

Typically, an object to be built is first created as a 3Ddigitally-modeled image. Using common computer-aided design (CAD)software, the modeled image is virtually created. After that, the objectmodel is virtually “sliced” into thin layers, which ultimately compriseinstructions of how the model will be physically built by the 3Dprinter. This virtual “slicing” is needed because conventional methodsof 3D-printing involve a print head that successively deposits materialin thin layers according to the geometry of the modeled image based onthe printing instructions for each layer. The physical object is thenproduced by depositing successive layers of material one on top ofanother, according to the layer-instructions, from bottom to top. Theprint head is capable of depositing the heated material while moving inmultiple linear directions, while the base moves in three-dimensions.The print head continues depositing the material until the top, or last,layer of the object is reached and the object is thus fully formed.

Numerous methods of powder based 3D-printing have been developed.Selective laser sintering (SLS) is a 3D-printing technique that uses alaser to fuse powder material on successive layers based on the geometryof the 3D model. High speed sintering (HSS) and Multi jet fusion (MJF)3D-printing employ multiple jets that similarly deposit successivelayers of IR absorbing ink onto powder material, followed by exposure toIR energy for selective melting of the powder layer. Electrophotography3D-printing employs a rotating photoconductor that builds the objectlayer-by-layer from the base.

SLS, MJF, and HSS 3D-printing share the same type of free floating,non-fixed, powder bed used for the production of the object. They sharethe same material requirements for compatibility with the printingprocess since the free body diagram of the additively built object willhave the same stresses applied, only with different heating mechanismsto obtain the melt phase. The free body diagram of a 3D printed objectcan be used to determine the residual stresses expected in the object.This is necessary for successfully building the object. If the residualstress is too high, the object will deform into the printing region andbe displaced in the part bed by the printing processes such as thepowder deposition blade or roller.

The prior art identifies many ways to address residual stresses. Ingeneral, to obtain the lowest amount of residual stress in a freefloating powder bed, both the modulus and the volumetric change of themolten phase should be suitably low. This is so the selectively moltenareas do not induce large enough residual stresses into the object thatit leaves a build plane. The most common process for addressing residualstresses for these powder bed-based 3D printers, is to use a polymerwith a sufficiently large operating window between its meltingtemperature and its recrystallization temperature. Therefore, keepingthe molten region a low modulus and uncrystallized minimizes largestrain until the entire object is built. Unfortunately, few polymershave a broad enough window between the two aforementioned phasetransitionals to allow the SLS and MJF processes to build the objectwith a low enough residual stress.

Thus, when choosing 3D-printing materials the breadth of the operatingwindow is a significant process parameter. Physical characteristics of asuitable polymer include a melting temperature that is higher than itsrecrystallization temperature, and a suitability for effective localizedmelting.

Specifically, the operating window should be such that the selectivelymelted polymer exhibits a modulus that is low enough to not createproblematic residual stresses in the printed object while cooling to thepart bed temperature. And at the part bed temperature, no formation ofcrystallites is observed. Specifically, the window should be such thatthe polymer effectively melts at a low enough modulus that it does notinduce residual stress on the printed object during cooling. Ifachieved, there is no substantive volumetric change through therecrystallization temperature in the object, until the entire object isbuilt. If the operating window of the polymer is too small, a build-upof stresses occurs, in part, because the polymer shrinks during thebuild.

It is, therefore, the gap size between the melting point and therecrystallization temperature of the polymer that forms a suitableoperational window to better allow for polymer printing in SLS, HSS, andMJF 3D-printing systems. To expand the range of available usablematerials in these printing systems, the physical properties of thepolymers, and processes that may change their physical properties andexpand the operating windows, must be considered.

Other polymers, such as thermoplastic elastomers (TPE) may exhibit a lowenough modulus, that operating outside of the typical operating windowdoes not result in the failure of a part build, but rather higher thandesired porosity. That said, having a higher melting point, larger andor more crystallites, and a lower recrystallization temperature arestill desired. This is because a higher melting point will enable ahigher part bed temperature, create larger and/or more crystallites thatprevent unwanted part growth in the part bed (defined as when the powdernear the selectively melted polymer also melts), and lower therecrystallization temperature.

SUMMARY

The disclosed exemplary apparatuses, systems, and methods provide powderpolyether block amides, thermoplastic polyeurothanes, and/orthermoplastic olefins formed through chemical precipitation to create anincreased operating window for use in SLS, MJF, HSS, andelectrophotography 3D-printing applications. An embodiment of thedisclosure may provide a precipitated pulverulent polymer formed throughprecipitating the polymer in a solvent, allowing the polymer to formcrystallites, and then employing the precipitated pulverulent polymer ina powder-based 3D-printing process.

A polymer material suitable for three-dimensional printing may includeat least one polymer selected from the group consisting of polyetherblock amides, thermoplastic polyeurothanes, and thermoplastic olefins.The at least one polymer is formed through chemical precipitation to aprecipitated pulverulent polymer which possesses increased operatingwindow characteristics. Said characteristics are selected from the groupconsisting at least one of a wider than typical range between and amongthe melting and recrystallization temperatures, a larger enthalpy uponmelting, and a low volumetric change during recrystallization.

In the above and other illustrative embodiments, the polymer materialmay further comprise: having a particle geometry not formed from millingincluding cryogenic milling; having increased operating windowcharacteristics for selective laser sintering, multi jet fusion, or highspeed sintering three-dimensional printing applications; a precipitatedpulverulent polymer which includes a melting temperature that is higherthan its recrystallization temperature, and melting characteristicssuitable for effective localized melting; being sinterable from aboutroom temperature to less than about 150 degrees Celsius; and beingproduced through chemical precipitation and having a particle size rangefrom about 25 microns to about 75 microns.

Another illustrative embodiment of the present disclosure may comprise aprecipitated pulverulent polymer formed by one or more of the following:a first precipitation process comprising: mixing one or more of thepolymers into a solution of toluene and eicosapentaenoic acid forming acomposition; adding a stabilizer to the composition; stirring thecomposition; heating the composition to boil; boiling off theeicosapentaenoic acid from the composition; and drying the precipitatedpolymer powder; a second precipitation process comprising: dissolvingone or more of the polymers in ethanol forming a composition; heatingthe composition; and precipitating the polymer into a crystallinepowder; a third precipitation process comprising: melting one or more ofthe polymers in nitrogen in an autoclave and heating contents in theautoclave to a temperature above 200 degrees Celsius; increasing thepressure in the autoclave; maintaining the pressure in the autoclavewhile heating the contents to over 250 degrees Celsius; depressurizingthe autoclave while holding-in the nitrogen; and drying any resultingpolymer powder; a fourth precipitation process comprising: adding one ormore of the polymers to a container with ethanol denatured with2-butanone and about 1% water forming a composition; heating thecomposition to above 130 degrees Celsius for about an hour; cooling thecomposition; and removing the ethanol through distillation; a fifthprecipitation process comprising: mixing one or more polymers withlaurolactam, 1,12-dodecanedioic acid, water, and aqueous hypophosphorousacid to form a composition; heating the composition in an autoclave;maintaining autogenic pressure from the composition in the autoclave;stirring the composition in the autoclave; depressurizing the autoclaveto atmospheric pressure; and passing nitrogen over the composition; anda sixth precipitation process comprising: adding one or more polymers toa tank; heating the polymer to above 140 degrees Celsius; stirring thepolymer in the tank; adding ethanol denatured with 2-butanone and waterto the tank forming a composition; holding the composition at theelevated temperature for a period of time; reducing the heat; removingthe ethanol by distillation while stirring the composition; and dryingthe composition.

Another illustrative embodiment of the present disclosure provides oneor more polymer materials suitable for three-dimensional printing,comprising at least one or more of the following characteristics: theone or more polymer being one or more polyether block amide,thermoplastic polyeurothane, and/or thermoplastic olefin; the one ormore polymer being any polyether block amide made from polycondensationof a carboxylic acid polyamide and an alcohol termination polyether; theone or more polymer being any thermoplastic or thermoplasticpolyurethane that includes a linear segmented block of polymers; the oneor more polymer being any blend of polyether block amide, thermoplasticpolyeurothane, and/or thermoplastic olefin; the one or more polymerformed through chemical precipitation; the one or more polymer being aprecipitated pulverulent polymer; the one or more polymer particlegeometry formed from chemical precipitation; the one or more polymerparticle geometry not formed from milling including cryogenic milling;the one or more polymer being a precipitated pulverulent polymerpossessing increased operating window characteristics useful inselective laser sintering, multi jet fusion, high speed sintering, andpossibly electrophotography three dimensional printing applications; theprecipitated pulverulent polymer possessing increased operating windowcharacteristics that includes at least one of: a wider than typicalrange between and among the melting and recrystallization temperatures,a larger enthalpy upon melting, and low volumetric change duringrecrystallization for a given polymer; the precipitated pulverulentpolymer includes a melting temperature that is higher than itsrecrystallization temperature, and melting characteristics suitable foreffective localized melting; the precipitated pulverulent polymerincludes characteristics that allow for an operating window that keeps aportion of the material unmelted, near the presence of a laser or nearthe selectively deposited fusing agent when heated via IR heater usedduring 3D-printing, in solid form so the unmelted solid material acts asa supporting structure for any molten polymer; the precipitatedpulverulent polymer includes particles that soften at low temperaturesbut do not fuse together until exposed directly to the heat source, suchas the laser or IR heater; the precipitated pulverulent polymer may besinterable from about room temperature to less than about 150 degreesCelsius; the precipitated pulverulent polymer does not suffer thermaldegradation during the printing process; the precipitated pulverulentpolymer produced through chemical precipitation has a more stable andprint-suitable particle size and geometry, spherical geometry, less needfor flow agent, particle size control, and tight distribution ofparticle geometries; the precipitated pulverulent polymer producedthrough chemical precipitation has an optimum particle-size and geometryrange to balance between cohesion and object detail; the precipitatedpulverulent polymer produced through chemical precipitation has aparticle size range from about 25 microns to about 75 microns; theprecipitated pulverulent polymer during three-dimensional printing coolsconcurrently when an object is finished printing; the precipitatedpulverulent polymer having a particle-size distribution determined bylaser scattering; the precipitated pulverulent polymer having a meltingpoint and enthalpy determined through Differential Scanning calorimetry;the precipitated pulverulent polymer having a powder flow measured usingMethod A of VIN EN ISO 6186; and the precipitated pulverulent polymerhaving a modulus of elasticity and tensile strength determined pursuanta DIN/EN/ISO 527 standard.

BRIEF DESCRIPTION OF THE DRAWINGS

The exemplary apparatuses, systems, and methods shall be describedhereinafter with reference to the attached drawing which is given as anon-limiting example only, in which:

FIG. 1 is a differential scanning calorimetry diagram of a non-use TPUpowder designed for 3D-printing;

FIG. 2 is a differential scanning calorimetry diagram of an exemplaryprecipitated TPU and baseline TPU;

FIG. 3 is a flow chart depicting an illustrative process according tothe present disclosure; and

FIG. 4 is a flow chart depicting an illustrative process of making aprecipitated pulverulent polymer.

DETAILED DESCRIPTION

The figures and descriptions provided herein may have been simplified toillustrate aspects that are relevant for a clear understanding of theherein described apparatuses, systems, and methods, while eliminating,for the purpose of clarity, other aspects that may be found in typicalsimilar devices, systems, and methods. Those of ordinary skill may thusrecognize that other elements and/or operations may be desirable and/ornecessary to implement the devices, systems, and methods describedherein. But because such elements and operations are known in the art,and because they do not facilitate a better understanding of the presentdisclosure, for the sake of brevity a discussion of such elements andoperations may not be provided herein. However, the present disclosureis deemed to nevertheless include all such elements, variations, andmodifications to the described aspects that would be known to those ofordinary skill in the art.

Embodiments are provided throughout so that this disclosure issufficiently thorough and fully conveys the scope of the disclosedembodiments to those who are skilled in the art. Numerous specificdetails are set forth, such as examples of specific components, devices,and methods, to provide a thorough understanding of embodiments of thepresent disclosure. Nevertheless, it will be apparent to those skilledin the art that certain specific disclosed details need not be employed,and that embodiments may be embodied in different forms. As such, theembodiments should not be construed to limit the scope of thedisclosure. As referenced above, in some embodiments, well-knownprocesses, well-known device structures, and well-known technologies maynot be described in detail.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. For example, asused herein, the singular forms “a”, “an” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The steps, processes, and operations described herein are notto be construed as necessarily requiring their respective performance inthe particular order discussed or illustrated, unless specificallyidentified as a preferred or required order of performance. It is alsoto be understood that additional or alternative steps may be employed,in place of or in conjunction with the disclosed aspects.

When an element or layer is referred to as being “on”, “upon”,“connected to” or “coupled to” another element or layer, it may bedirectly on, upon, connected or coupled to the other element or layer,or intervening elements or layers may be present, unless clearlyindicated otherwise. In contrast, when an element or layer is referredto as being “directly on,” “directly upon”, “directly connected to” or“directly coupled to” another element or layer, there may be nointervening elements or layers present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.). Further, as used herein the term “and/or” includes anyand all combinations of one or more of the associated listed items.

Yet further, although the terms first, second, third, etc. may be usedherein to describe various elements, components, regions, layers and/orsections, these elements, components, regions, layers and/or sectionsshould not be limited by these terms. These terms may be only used todistinguish one element, component, region, layer or section fromanother element, component, region, layer or section. Terms such as“first,” “second,” and other numerical terms when used herein do notimply a sequence or order unless clearly indicated by the context. Thus,a first element, component, region, layer or section discussed belowcould be termed a second element, component, region, layer or sectionwithout departing from the teachings of the embodiments.

The present disclosure relates to pulverulent precipitated polyetherblock amides (PEBA), thermoplastic polyurethanes (TPU), andthermoplastic olefins (TPO), that possess increased operating windowcharacteristics useful in, for example, SLS, MJF, HSS, and possiblyelectrophotography 3D-printing applications. For purposes of thisdisclosure, an “increased operating window” includes the characteristicsof at least one of a wider than typical range between and among themelting and recrystallization temperatures, a larger enthalpy uponmelting, and lower volumetric change during recrystallization for agiven TPE.

Illustrative polymers that are within the scope of this disclosureinclude, but are not limited to, varieties PEBAs, TPOs, and TPU's. SuchPEBA's contemplated to be within the scope of the disclosure include, byway of non-limiting example, PEBAX (Arkema) polyether block amide,Vestamid E (Evonik) polyether block amide, Santoprene (ExxonMobil) blockcopolymer, Termoton (Termopol Polimer) block copolymer, Arnitel (DSM)block copolymer, Solprene (Dynasol) block copolymer, Engage (Dow) blockcopolymer, Dryflex (Elasto) block copolymer, Mediprene (Elasto) blockcopolymer, and Kraton (Kraton Polymers). Of course, it will beappreciated by the skilled artisan, in light of the discussion herein,that other PEBAs suitable to gain an increased operating window for3D-printing using the methodologies referenced below, is contemplated tobe within the scope of this disclosure. PEBAs made from polycondensationof a carboxylic acid polyamide and an alcohol termination polyether, aresimilarly contemplated to be within the scope of this disclosure aswell. Similarly, thermoplastic olefins that include a fraction ofthermoplastic, elastomer, and filler, may be contemplated within thescope of this disclosure.

Thermoplastic polyurethanes of the type contemplated in this disclosureillustratively include Texin (Bayer) thermoplastic polyurethane,Elastollan (BASF) thermoplastic polyurethane, Doesmopan (Covestro)thermoplastic polyurethane, Estane (Lubrizol) thermoplasticpolyurethane, Irogran (Huntsman) thermoplastic polyurethane, Avalon(Huntsman) thermoplastic polyurethane, Isothane (Greco) thermoplasticpolyurethane, Zythane (Alliance) thermoplastic polyurethane, Tekron(Teknor) thermoplastic elastomer, Elexar (Teknor) thermoplasticelastomer. It will also be appreciated, based on the disclosure herein,that any thermoplastic and particularly thermoplastic polyurethane thatincludes a linear segmented block of polymers may be within the scope ofthe embodiments.

It is further contemplated that blends of one or more of the abovepolymers may be included within the scope of this disclosure. Futher, itwill be understood to the skilled artisan, in light of this discussionof the embodiments herein, that flow agents and fillers may beincorporated into, and/or into the disclosed methodologies to produce,the disclosed precipitated pulverulent polymers.

As referenced, embodiments of the present disclosure provideprecipitated pulverulent ones of the afore-discussed thermoplasticelastomers (including polyether block amides) and thermoplasticpolyurethanes that possess increased operating window characteristics,such as for enhanced use in SLS, MJF, HSS, and possiblyelectrophotography 3D-printing applications. Physical characteristics ofsuitable precipitated pulverulent polymers each include a meltingtemperature that is higher than its recrystallization temperature, andmelting characteristics suitable for effective localized melting. Thesecharacteristics allow for an operating window that keeps the rest of thematerial unmelted, such as even in the presence of a laser or IR heaterused during 3D-printing in solid form. The unmelted solid material canthen act as a supporting structure for the molten polymer.

For purposes of this disclosure, an increased operating window includesthe characteristics of at least one of a wider range between the meltingand recrystallization temperatures, a larger enthalpy upon melting, andlow volumetric change during recrystallization. By modifying thepolymer's characteristics, its particles may soften at lowertemperatures but do not fuse together until exposed directly to the heatsource, such as the laser. It is appreciated that these polymers may besinterable from about room temperature to less than 150 degrees Celsius.With these glass transition temperatures (Tg) and sinter temperaturesranges it is less likely the polymers will suffer thermal degradationduring the printing process, among other advantages.

Powder-based 3D-printing includes a part bed and feed bed. This part bedis generally at a steady temperature before it is subjected to an energysource. That energy source is raised until a fusion temperature isreached. Material is placed on a feed bed at a start temperature. Duringoperation additional material is placed on top of the original materialwhich cools and needs to be raised again. If the polymer does not havelarge enough crystallite or enough mass in the crystallites to be ableto absorb excess energy to stay crystalline, and if there is too muchheat it starts melting the feed bed material causing unexpected moltenpolymer called growth. It is preferred to only melt the portion ofpolymer that is directly subjected to energy and not the surroundingpoloymer. With larger crystallites and higher melting temperature, moreenergy to melt those crystallites is needed which means there is lessgrowth from the feed bed material. It is believed precipitating thepolymer will create larger crystallites to limit this growth.

A common prior method of modifying these polymers to achieve some of theforegoing advantages is through milling, such as cryogenic milling Incontrast to milling, however, chemical precipitation better enhances thepolymers' operating windows and additional printing characteristics. Achemically precipitated polymer also provides a more stable andprint-suitable particle size and geometry. For SLS, HSS, and MJF3D-printing applications, there tends to be an optimum particle-size andgeometry range to balance between cohesion and object detail. If thepolymer's particle size is too small it becomes too powdery and has atendency to clump during printing. In contrast, if the polymer'sparticle size is too large, fine features and details on the printedobject become lost.

Optimum particle size ranges provided by the disclosed embodiments mayrange from about 25 microns to about 75 microns. Deviating downwardabout 8 microns to about 10 microns from this range increases the riskof clumping issues, depending on the desired printing environment. Onthe other hand, if the particle size is deviated upwards a significantamount from the foregoing range, the polymer's ability to produce finedetail on an object may no longer be possible. Hence, the chemicalprecipitation aspects disclosed produce average particle sizes withinthe optimum 25 microns through 75 microns range. Typical particle sizesmay range over a much more significant variation, such as from 5 micronsto 500 microns.

Milled polymers in the known art also produce particles with geometriesthat may decrement 3D print performance, such as particles having jaggedand fractured edges. This is, in part, because the milling does notprovide a rounding-type grinding action, but rather provides more of ashear grinding. By contrast, the disclosed chemical precipitationtechniques for polymers provide particles with much more sphericalgeometry. This translates into particle size and physical characteristicstability, less need for flow agents or additives, and better particlesize control in polymer blends. The disclosed precipitated polymers alsohave a tight distribution of particle geometries, which may bebeneficial for their physical characteristics in SLS and MJF 3D-printingapplications.

A differential scanning calorimetry (DSC) diagram showing the phasetransitions of an exemplary non-use TPU specifically designed for3D-printing is shown in FIG. 1. This prior art TPU been corrected fornon-heat flow which accounts for its flat curve. It shows severaldifferent melting peaks that and several different crystallitesavailable ranging from about 60 degrees C. up to about 150 and about210. It has a recrystallization temperature starting at about 90 degreesC.

Precipitation methods may also create pulverulent polymers that have themelting temperatures and enthalpy needed to obtain proper powder meltingcharacteristics during SLS, HSS, and MJF 3D-printing. FIG. 2 shows DSCdiagrams of a baseline TPU and an exemplary precipitated TPU. Thebaseline TPU, identified in the graph as 1.1 and 1.3, is anoff-the-shelf TPU not specifically designed for 3D-printing. Theprecipitated TPU was also not designed specifically for 3D-printing andis identified as 2.1 and 2.3 in the graph. During melting theprecipitated TPU 2.1 demonstrates larger crystallites than the basepolymer 1.1. It appears the baseline has about 1 joule per gram ofmelting enthalpy where the precipitated TPU developed two differenttypes of crystallites present of about 5 and about 7 joules per gram,respectively. With regard to recrystallization temperature, the baselineTPU 1.3 appears to have a recrystallization temperature of about 105degrees Celsius. Recrystallization of precipitated polymer had not beenobserved yet at about 90 degrees Celsius. It unexpectedly appeared thatthe recrystallization temperature shifted. Also, because there is nosharp peak on the 2.3 line like there is on the 1.3 line it appears thatthe recrystallization may have slowed.

A variety of methods to chemically precipitate the above-identifiedpolymers may be employed. One skilled in the art will appreciate, basedon illustrative methods described below, that other precipitationmethods may be employed in the embodiments though they are notexplicitly disclosed herein.

As will be further appreciated to the skilled artisan, in light of thediscussion and the embodiments herein, an illustrative embodiment mayprovide adding a polymer to a solvent and precipitating it to allow thepolymer to form larger, thicker crystallites which produce the foregoingoperating window for power-based 3D-printing. FIG. 3 is a flow chartthat illustratively depicts such an embodiment of the disclosure. Thisprocess includes placing a polymer in a solvent at reference numeral 32known for use with that solvent. At reference numeral 34 the polymer isprecipitated to form larger crystallites which are believed to providedesired characteristics of higher melting temperature and broaderoperating window based on the desired precipitation size. It is furtherbelieved solvent-based precipitation of the polymer produces a moreordered crystalline structure because the polymer chains have moremobility to conform and form the crystallites during this process. Theprecipitated polymer is then used in powder-based 3D-printing (i.e.,SLS, HSS, and MJF printing) as depicted at reference numeral 36.

Accordingly, characteristics of pulverulent precipitated polymers do notproduce a large volumetric change until the entire object is builtduring SLS, HSS, and MJF 3D-printing. When 3D-printing an object, it isdetrimental to experience crystallinity in the plastic before the objectis completed. The entire object should be in an isotherm, or about thesame temperature, so it does not undergo crystallization. Otherwise, amoment of irregularity in the crystallization may be produced whileprinting, which may lead to a catastrophic stress or strain. Likewise,if one part of the object crystallizes before another part, theirregular moments may cause the object to distort.

An illustrative method of making the precipitated pulverulent polymerincludes a mixture of the polymer, toluene, eicosapentaenoic acid (EPA),and water. An illustrative flow chart depicting this exemplary process40 is shown in FIG. 4. The process includes first mixing any of theforegoing polymers into a solution of toluene and EPA as shown at 42.Water is added and the composition is heated as depicted at 44 andstirred at 46. A stabilizer may be added to stabilize the toluene at 44.The composition continues to heat until it boils as indicated at 48.Continued boiling causes the EPA to boil off at 50, leaving theprecipitated polymer powder which is then dried at 52. It is noted thatthis process is believed to form controlled-size powders.

Particle-size distribution may be determined by laser scattering.Melting point and enthalpy may be determined through DSC. Powder flowmay be measured using Method A of VIN EN ISO 6186. Modulus of elasticityand tensile strength maybe determined pursuant the DIN/EN/ISO 527standard.

It is appreciated that the polymers may be mixed in different ratios andparticle sizes. This may have the effect of changing or controlling theproperties of the resulting pulverulent powdered polymer.

It is further contemplated that the above-identified polymers may bedeveloped in powdered form through other methods of chemicalprecipitation. Other such examples include dissolving the polymer, orpolymers in ethanol and precipitating the polymer(s) into a crystallinepowder.

An alternate method of chemical precipitation of one or more of theabove-identified polymers may include melting the one or more of thepolymers in nitrogen at a temperature above 200 degrees Celsius. Thecomposition is placed in an autoclave where the internal pressure isincreased. Pressure is maintained while heating to over 250 degreesCelsius. The autoclave is depressurized while holding-in the nitrogen.The resulting material is then dried.

Another method of chemically precipitating the polymers may includeadding one or more of the above-identified polymers in a container withethanol denatured with 2-butanone and about 1% water. The composition isthen heated to above 130 degrees Celsius for about an hour. Thecomposition is then cooled and ethanol removed through distillation. Theprecipitated polymers form during cooling.

In another embodiment, laurolactam, is mixed with 1,12-dodecanedioicacid, water, and aqueous hypophosphorous acid. The composition is heatedand maintains autogenic pressure in an autoclave where it is alsostirred. The heat and pressure is held for a first period of time. Thecomposition is depressurized to atmospheric pressure and nitrogen passedover for a second period of time to form the polymer.

In another embodiment, the polymer or polymers may be heated above 140degrees Celsius and stirred in a tank. Ethanol denatured with 2-butanoneand water are added to the tank. The composition is held at the elevatedtemperature for a period of time and stirred. The heat is then reducedand the ethanol removed via distillation while the composition is stillbeing stirred. Once precipitation starts, the distillation rate isincreased until the internal temperature of the composition lowers. Thecomposition is then dried with any remaining ethanol removed throughfurther distillation.

It is appreciated that these polymers may also be re-precipitatedaccording to one or more of these above methods. It is furtherappreciated that different temperatures, pressures, times, and stirrates may be applied to these precipitation methods to modify thevarious characteristics of the polymers.

In conjunction with the use of the above-identified polymers, a furtherillustrative embodiment includes adding a flow agent to the pulverulentpowdered polymer. Illustratively the flow agent may include one or more:fumed silicas, calcium silicates, alumina, amorphous alumina, magnesiumsilicates, glassy silicas, hydrated silicas, kaolin, attapulgite, glassyphosphates, glassy borates, glassy oxides, titania, talc, pigments, ormica. The particle size of these flow agents may be about 10 microns orless. Additionally, they are included only to the extent they enhancethe flow of the polymer material. In an illustrative embodiment, theflow agent may be blended with the pulverulent precipitated polymer(s).It is appreciated that the amount of flow agent used should notsignificantly alter the Tg of the polymer(s). Illustratively, the flowagent will be present in an amount less than 5% by weight of thecomposition.

Because the polymer powders of the present disclosure are precipitatedrather than milled, they have particles with much more sphericalgeometry. This means there is less need for flow agents or additives.And if a flow agent is added, much less than what may otherwise berequired for milled powders. With precipitated polymers, the flow agentjust needs to assist the powdered polymer to level when poured into acontainer. It is also appreciated that the flow agent is introduced toonly dry powder polymer, and only blended to the extent there is asufficient distribution of the agent. Static electricity may build up inthe powder if over-mixed which may limit the powder's ability to levelwhen poured into a container.

Another illustrative embodiment of the present disclosure may includeadding compatible fillers to the powdered polymers. These fillers may beorganic or inorganic. Such fillers may include pigments, glass, ceramic,or metal, in particulate, or bead form. In this illustrative embodimentfillers should have particle sizes equal to or less than the averageparticle size of the corresponding powdered polymer. Additionally, thefillers may occupy up to about 25% by weight of the entire powder blend.

Further, the descriptions of the disclosure are provided to enable anyperson skilled in the art to make or use the disclosed embodiments.Various modifications to the disclosure will be readily apparent tothose skilled in the art, and the generic principles defined herein maybe applied to other variations without departing from the spirit orscope of the disclosure. Thus, the disclosure is not intended to belimited to the examples and designs described herein, but rather is tobe accorded the widest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A polymer material suitable for three-dimensionalprinting, comprising: at least one polymer selected from the groupconsisting of polyether block amide, thermoplastic polyeurothane, andthermoplastic olefin; wherein the at least one or more polymer formedthrough chemical precipitation forming a precipitated pulverulentpolymer; wherein the precipitated pulverulent polymer possessesincreased operating window characteristics selected from the groupconsisting at least one of a wider than typical range between and amongthe melting and recrystallization temperatures, a larger enthalpy uponmelting, and a low volumetric change during recrystallization.
 2. Thepolymer material of claim 1, wherein the at least one or more polymerhas a particle geometry not formed from milling including cryogenicmilling.
 3. The polymer material of claim 1, wherein the at least one ormore polymer has increased operating window characteristics forselective laser sintering, multi jet fusion, or high speed sinteringthree dimensional printing applications;
 4. The polymer material ofclaim 1, wherein the precipitated pulverulent polymer includes a meltingtemperature that is higher than its recrystallization temperature, andmelting characteristics suitable for effective localized melting.
 5. Thepolymer material of claim 1, wherein the precipitated pulverulentpolymer may be sinterable from about room temperature to less than about150 degrees Celsius.
 6. The polymer material of claim 1, wherein theprecipitated pulverulent polymer produced through chemical precipitationhas a particle size range from about 25 microns to about 75 microns. 7.The polymer material of claim 1, wherein the precipitated pulverulentpolymer is formed through precipitating the polymer in a solvent andallowing the polymer to form crystallites.
 8. The polymer material ofclaim 1, wherein the precipitated pulverulent polymer is formed by oneor more of the following: a first precipitation process comprising:mixing one or more of the polymers into a solution of toluene andeicosapentaenoic acid forming a composition; adding a stabilizer to thecomposition; stirring the composition; heating the composition to boil;boiling off the eicosapentaenoic acid from the composition; and dryingthe precipitated polymer powder; a second precipitation processcomprising: dissolving one or more of the polymers in ethanol forming acomposition; heating the composition; and precipitating the polymer intoa crystalline powder; a third precipitation process comprising: meltingone or more of the polymers in nitrogen in an autoclave and heatingcontents in the autoclave to a temperature above 200 degrees Celsius;increasing the pressure in the autoclave; maintaining the pressure inthe autoclave while heating the contents to over 250 degrees Celsius;depressurizing the autoclave while maintaining the nitrogen in theautoclave; and drying any resulting polymer powder; a fourthprecipitation process comprising: adding one or more of the polymers toa container with ethanol denatured with 2-butanone and about 1% waterforming a composition; heating the composition to above 130 degreesCelsius for about an hour; cooling the composition; and removing theethanol through distillation; a fifth precipitation process comprising:mixing one or more polymers with laurolactam, 1,12-dodecanedioic acid,water, and aqueous hypophosphorous acid to form a composition; heatingthe composition in an autoclave; maintaining autogenic pressure from thecomposition in the autoclave; stirring the composition in the autoclave;depressurizing the autoclave to atmospheric pressure; and passingnitrogen over the composition; and a sixth precipitation processcomprising: adding one or more polymers to a tank; heating the polymerto above 140 degrees Celsius; stirring the polymer in the tank; addingethanol denatured with 2-butanone and water to the tank forming acomposition; holding the composition at the elevated temperature for aperiod of time; reducing the heat; removing the ethanol by distillationwhile stirring the composition; and drying the composition.
 9. One ormore polymer materials suitable for three-dimensional printing,comprising at least one or more of the following characteristics: theone or more polymer being one or polyether block amide, thermoplasticpolyeurothane, and thermoplastic olefin; the one or more polymer beingany thermoplastic elastomer having thermoplastic and elastomericproperties; the one or more polymer being any polyether block amide madefrom polycondensation of a carboxylic acid polyamide and an alcoholtermination polyether; the one or more polymer being any thermoplasticor thermoplastic polyurethane that includes a linear segmented block ofpolymers; the one or more polymer being any blend of polyether blockamides, thermoplastic polyeurothanes, or thermoplastic olefins; the oneor more polymer formed through chemical precipitation; the one or morepolymer being a precipitated pulverulent polymer; the one or morepolymer particle geometry formed from chemical precipitation; the one ormore polymer particle geometry not formed from milling includingcryogenic milling; the one or more polymer being a precipitatedpulverulent polymer possessing increased operating windowcharacteristics useful in selective laser sintering, multi jet fusion,or high speed sintering three dimensional printing applications; theprecipitated pulverulent polymer possessing increased operating windowcharacteristics that includes at least one of: a wider than typicalrange between and among the melting and recrystallization temperatures,a larger enthalpy upon melting, and low volumetric change duringrecrystallization for a given polymer; the precipitated pulverulentpolymer includes a melting temperature that is higher than itsrecrystallization temperature, and melting characteristics suitable foreffective localized melting; the precipitated pulverulent polymerincludes characteristics that allow for an operating window that keeps aportion of the material unmelted, even in the presence of a laser or IRheater used during 3D-printing, in solid form so the unmelted solidmaterial acts as a supporting structure for any molten polymer; theprecipitated pulverulent polymer includes particles that soften at lowtemperatures but do not fuse together until exposed directly to the heatsource, such as the laser or IR heater; the precipitated pulverulentpolymer may be sinterable from about room temperature to less than about150 degrees Celsius; the precipitated pulverulent polymer does notsuffer thermal degradation during the printing process; the precipitatedpulverulent polymer produced through chemical precipitation has a morestable and print-suitable particle size and geometry, sphericalgeometry, less need for flow agent, particle size control, and tightdistribution of particle geometries; the precipitated pulverulentpolymer produced through chemical precipitation has an optimumparticle-size and geometry range to balance between cohesion and objectdetail; the precipitated pulverulent polymer produced through chemicalprecipitation has a particle size range from about 25 microns to about75 microns; the precipitated pulverulent polymer duringthree-dimensional printing cools concurrently when an object is finishedprinting; the precipitated pulverulent polymer having a particle-sizedistribution determined by laser scattering; the precipitatedpulverulent polymer having a melting point and enthalpy determinedthrough Differential Scanning calorimetry; the precipitated pulverulentpolymer having a powder flow measured using Method A of YIN EN ISO 6186;and the precipitated pulverulent polymer having a modulus of elasticityand tensile strength determined pursuant a DIN/EN/ISO 527 standard. 10.The one or more polymer materials of claim 9, wherein the precipitatedpulverulent polymer is formed by one or more of the following: a firstprecipitation process comprising: mixing one or more of the polymersinto a solution of toluene and eicosapentaenoic acid forming acomposition; adding a stabilizer to the composition; stirring thecomposition; heating the composition to boil; boiling off theeicosapentaenoic acid from the composition; and drying the precipitatedpolymer powder; a second precipitation process comprising: dissolvingone or more of the polymers in ethanol forming a composition; heatingthe composition; and precipitating the polymer into a crystallinepowder; a third precipitation process comprising: melting one or more ofthe polymers in nitrogen in an autoclave and heating contents in theautoclave to a temperature above 200 degrees Celsius; increasing thepressure in the autoclave; maintaining the pressure in the autoclavewhile heating the contents to over 250 degrees Celsius; depressurizingthe autoclave while holding-in the nitrogen; and drying any resultingpolymer powder; a fourth precipitation process comprising: adding one ormore of the polymers to a container with ethanol denatured with2-butanone and about 1% water forming a composition; heating thecomposition to above 130 degrees Celsius for about an hour; cooling thecomposition; and removing the ethanol through distillation; a fifthprecipitation process comprising: mixing one or more polymers withlaurolactam, 1,12-dodecanedioic acid, water, and aqueous hypophosphorousacid to form a composition; heating the composition in an autoclave;maintaining autogenic pressure from the composition in the autoclave;stirring the composition in the autoclave; depressurizing the autoclaveto atmospheric pressure; and passing nitrogen over the composition; anda sixth precipitation process comprising: adding one or more polymers toa tank; heating the polymer to above 140 degrees Celsius; stirring thepolymer in the tank; adding ethanol denatured with 2-butanone and waterto the tank forming a composition; holding the composition at theelevated temperature for a period of time; reducing the heat; removingthe ethanol by distillation while stirring the composition; and dryingthe composition.
 11. The polymer material of claim 1, wherein thepolymer material may be blended with a cross linked hollow elastomericmicrospheres suitable to form a three-dimensional object.